Husband was bit by a black fly 3 days ago. he's since had bad joint pain and swelling. he is feeling exhausted and just not himself. is this normal?

No it's not normal: It's a immune or allergic reaction to an insect bite, which needs to be evaluated asap, since he is exhausted . Must seek treatment, .

Agree w Dr.: Poochikian. This is not normal & warrants medical care. The bite of the black fly can cause itching & marked local swelling which may continue for weeks. Allergic reactions can also occur. With heavy biting Black Fly Fever can occur with symptoms to include fever, headache, nausea & swollen lymph nodes. Secondary infection may occur.